Razor blade and method of manufacture

ABSTRACT

An elongated stock material for use in manufacturing shaving razor blades, the material including an elongated, flat strip of metal having a front edge and back edge extending along its length, a sharpened cutting edge portion extending along the front edge, a weakened portion between the front edge and the back edge, a blade portion between the cutting edge portion and the weakened portion, and a removable portion between the weakened portion and the back edge. Also disclosed are blades and cartridges made from the material, and methods and apparatus making and using the material.

This application is a continuation of U.S. patent application Ser. No.09/618,375 filed on Jul. 18, 2000, now U.S. Pat. No. 6,629,475.

TECHNICAL FIELD

This invention relates to shaving razor blades and stock material,manufacturing methods and apparatus therefor.

BACKGROUND

Razor blades are typically made from a continuous strip of stockmaterial that is hardened and sharpened while the strip travels along aprocessing line. The strip is then divided in blade length sections usedin manufacture of individual cartridges.

In some applications, blades are supported on bent supports that areslidably mounted in the cartridge housing to move up and down duringshaving. E.g., FIG. 1 shows cartridge 10 with blades 12 slidably mountedin housing 14, and FIG. 2 shows a blade 12 on a support 16. In theseapplications, the blades cannot overlap and thus have a small dimension“a ” from the cutting edge to the back edge 20. The strip material andblade sections, however, must have a sufficient distance from the frontedge to the back edge in order to properly secure and hold the materialand sections during processing and attaching to blade supports. It thusis necessary to remove a portion of the blade material after processingand attaching so that the blade will have the desired small dimensionfrom the cutting edge to the back edge. In some applications, the rearsection 22, shown in FIG. 3, is removed by bending the rear section 22between 60° and 90° with respect to the front section 24 after the frontsection has been attached to the blade support. FIG. 3 also shows spotweld 26, used to attach blade 12 to support 16. There typically is anupturned portion at the rear edge 20 of the attached blade section wherethe rear section has been removed. In some cases the rear section 22 isnot easily removed.

SUMMARY

In one aspect, the invention features, in general, an elongated stockmaterial for use in manufacturing shaving razor blades. The stockmaterial is made of an elongated, flat strip of metal having a frontedge and back edge extending along its length. The material has asharpened cutting edge portion extending along the front edge, aweakened portion between the front edge and the back edge, a bladeportion between the cutting edge portion and the weakened portion, and aremovable portion between said weakened portion and back edge.

In preferred embodiments, the weakened portion has a reduced thicknesscompared to the blade portion and the removable portion. The weakenedportion has a first notch portion on one side, and a second notchportion on the other side. The notch portions are offset with respect toeach other. Each notch portion has a steep surface and a graduallydeflecting surface. The weakened portion is located between ¼ and ¾ ofthe distance from the front edge to the back edge.

In another aspect the invention features, in general, a shaving razorblade including a metal blade having a front cutting edge portion and aback edge, the back edge having a weakened portion from which aremovable portion has been removed by bending at the weakened portion.

In preferred embodiments, the blade is mounted on a support memberattached to the metal blade. The support member has a base portion thatgenerally extends along a plane that makes an angle between 90 degreesand 135 degrees with a plane extending through the blade. The back edgehas a slight bend that is straighter than it would be if the separableportion did not have the weakened portion and has a radius instead of anupturned edge.

In another aspect, the invention features, in general, a shaving razorcartridge including a housing, and one or more blades attached to thehousing. Each blade having a front edge having a cutting edge portionand a back edge, the back edge having a weakened portion from which aremovable portion has been removed by separating at the weakenedportion.

In another aspect, the invention features, in general, a method ofmaking razor blades by providing an elongated, flat strip of metalhaving a front edge and back edge extending along its length, sharpeningthe front edge to result in a cutting edge portion extending along thefront edge, and weakening a portion of the strip along its lengthbetween the front edge and the back edge to result in a weakened portionextending along the strip, a blade portion between the cutting edgeportion and the weakened portion, and a removable portion between theweakened portion and the back edge.

In preferred embodiments, the weakening includes forming a crease toprovide the weakened portion. The weakening includes deforming a portionof the strip to reduce its thickness to provide the weakened portion.The weakening includes a notch formed on one or both sides of the strip.The strip is deformed by passing the elongated flat strip between tworollers. The deforming includes passing the elongated flat strip betweentwo rollers having different profiles and spaced sufficiently close toeach other to cause the portion of the strip to be deformed when passingbetween them. The strip is cut into discrete blade sections. The bladeportions of respective blade sections are attached to respective bladesupport members. The removable portions are separated from the bladeportions by bending at the weakened portions.

In another aspect, the invention features, in general, apparatus formaking razor blade material that includes a continuous supply of anelongated, flat strip of metal having a front edge and back edgeextending along its length, a processing line along which the flat stripfrom the supply moves, a sharpening station on the processing linethrough which the strip passes and at which the front edge is sharpenedto result in a cutting edge portion extending along the front edge, anda processing station on the processing line through which the strippasses and at which a portion of the strip between the front edge andthe back edge is weakened to result in a weakened portion extendingalong the strip, a blade portion between the cutting edge portion andthe weakened portion, and a removable portion between the weakenedportion and the back edge.

In preferred embodiments, the processing station includes two rollersthrough which the strip passes. The two rollers have different profilesand are spaced sufficiently close to each other to cause the portion ofthe strip to be deformed when passing between them. Each roller has alarge diameter portion and a small diameter portion, the large diameterportion of one the roller being generally aligned with the smalldiameter portion of the other the roller. Each roller has a thin portionbetween the small diameter portion and the large diameter portion, thethin portion having a diameter that is less than the diameter of thesmall diameter portion.

Embodiments of the invention may include one or more of the followingadvantages. Use of a weakened portion permits one to have a large widthto facilitate blade sharpening and attaching to a support, yet alsopermits a small distance from the cutting edge to the rear edge in thefinal shaving razor blade product. The use of a weakened portion alsopermits one to use a softer and higher corrosion resistant material thatotherwise would be difficult to separate by bending. The weakenedportion permits one to use different types of blade steel and steelprovided from various suppliers that normally will not fracture withoutsuch weakening. This can permit use of a smaller stock thickness (e.g.,0.002″ instead of 0.003″, as presently used), which generally is moredifficult to fracture. (I.e., thinner stock would be more likely to bendthan fracture).

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a shaving razor cartridge.

FIG. 2 is a section showing a prior art razor blade used in the FIG. 1cartridge.

FIG. 3 is a section showing the FIG. 2 blade prior to removal of a rearsection used to engage the blade during processing and attaching.

FIG. 4 is a section of a razor blade provided with a weakened section.

FIG. 5 is a section of a razor blade stock material used to make theFIG. 4 blade prior to sharpening.

FIG. 6 is side view of rollers used to provide a weakened portion in theFIG. 5 strip material.

FIG. 7 is a top view showing feeding of the strip material to the FIG. 6rollers.

FIG. 8 is a diagrammatic elevation of the FIG. 6 rollers shown with thestrip material in section.

FIG. 9 is a partial sectional view showing the weakened portion of theFIG. 4 blade in detail.

FIG. 10 is a section of the FIG. 4 razor blade after mounting on asupport and removal of a rear section.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Referring to FIG. 4, there is shown razor blade 30 having weakenedportion 32 between front section 34 and rear section 36. Front section34 includes cutting edge 38. Referring to FIG. 5, there is shown stripmaterial 40 having weakened portion 42 between front section 44 and rearsection 46. Weakened portions 32 and 42 are offset portions that areformed in strip material 40 during processing by passing the materialbetween rollers with offset portions. The weakened portions 32, 42 arelocated between ¼ and ¾ of the distance from the front edge to the backof the blade. Weakened portions 42 in the strip material (FIG. 5) havegenerally right angle edge portions, which become more rounded when thematerial is flattened during perforation, resulting in the rounded edgeportions in weakened portions 32 in blades 30° (FIG. 4).

Referring to FIGS. 6-8, strip material 40 (without a weakened portion42) is fed through strip guide 50 prior to passing between rollers 52,54. Each roller has guide rings 56 (FIG. 7) on the two sides. As isshown in FIG. 8, upper roller 52 as large diameter portion 60 spacedfrom small diameter portion 62 by neck region 64. Lower roller 54similarly has large diameter portion 66 and small diameter portion 68spaced by neck region 70. Each large diameter portion 60, 66 has adiameter that is 0.001 in. greater than the respective small diameterportion 62, 68. Large diameter portion 60 is generally aligned withsmall diameter portion 68 except that large diameter portion 60 extendsbeyond the edge of small diameter portion 68 in the offset region. Smalldiameter portion 62 is generally aligned with large diameter portion 66except that large diameter portion 66 extends slightly into the offsetregion. The stock material is 0.003 in. thick, and the spacing betweenmating portions of rollers 52 and 54 is 0.003 in.

Referring to FIG. 9, it is seen that weakened portion 32 of blade 30 hasnotch portion 70 on one side and notch portion 72 on the other. Thenotch portions 70, 72 are offset from each other, and each has a steepsurface 74 and a gradually deflecting surface 76.

Referring to FIG. 10, blade 30 is shown mounted on blade support 78after the rear section 36 has been removed. The rear section 36 isremoved by bending section 36 about 10 degrees with respect to the frontsection 34. The rear edge 80 of blade 30 advantageously has a radiusinstead of an upturned portion.

In addition to providing reduced upturn, the use of a weakened portionpermits one to use harder blade materials that otherwise could not beseparated by bending.

Other embodiments of the invention are within the scope of the followingclaims. For example, in addition to the offset notch crease, othercreasing methods could be used to provide the weakened region. Othertechniques could also be used to provide the weakened region. E.g., thematerial could be perforated, cut by laser beam or removed by grindingalong the length of the strip material to provide the weakened region.Grooving and scoring could also be carried out by a hard point tool suchas carbide, ceramic or diamond.

1. A method of making a shaving cartridge comprising a housing, a bladesupport member attached to the housing, and a blade attached to the badesupport member, comprising the steps of (a) providing an elongated, flatstrip of metal having a front edge and a back edge extending along itslength, (b) sharpening said front edge to result in a cutting edgeportion extending along said front edge, (c) weakening a portion of saidstrip along its length between said front edge and said back edge toresult in a weakened portion extending along said strip, a blade portionbetween said cutting edge portion and said weakened portion, and aremovable portion between said weakened portion and said back edge, (d)cutting said strip to result in discreet blade sections, each bladesection comprising part of the weakened portion, the blade portion, andthe removable portion, (e) attaching a blade section to the bladesupport member, and (f) separating the removable portion from the bladesection attached to the blade support member.
 2. The method of claim 1wherein said weakening includes forming a crease to provide saidweakened portion.
 3. The method of claim 1 wherein said weakeningincludes deforming a portion of said strip to reduce its thickness toprovide said weakened portion.
 4. The method of claim 3 wherein saiddeforming includes passing said elongated flat strip between tworollers.
 5. The method of claim 3 wherein said deforming includespassing said elongated flat strip between two rollers having differentprofiles and spaced sufficiently close to each other to cause saidportion of said strip to be deformed when passing between them.
 6. Themethod of claim 1 wherein said weakening includes forming a notch on aside of said strip to provide said weakened portion.
 7. The method ofclaim 1 wherein said weakening includes forming a first notch on oneside of said strip and a second notch on the other side of said strip toprovide said weakened portion.
 8. The method of claim 1 wherein saidseparating step is done by bending at said weakened portions.
 9. Themethod of claim 1, the shaving cartridge also including a second supportmember attached to the housing, wherein steps (e) and (f) are repeatedto attach a second blade section to the second support member and toseparate the removable portion from the second blade section.
 10. Amethod of making razor blades comprising the step of providing anelongated, flat strip of metal having a front edge and a back edgeextending along its length, sharpening said front edge to result in acutting edge portion extending along said front edge, and weakening aportion of said strip along its length between said front edge and saidback edge to result in a weakened portion extending along said strip, ablade portion between said cutting edge portion and said weakenedportion, and a removable portion between said weakened portion and saidback edge, wherein said weakening step includes deforming a portion ofsaid strip to reduce its thickness to provide said weakened portion,wherein said deforming step includes passing said elongated flat stripbetween two rollers having different profiles and spaced sufficientlyclose to each other to cause said portion of said strip to be deformedwhen passing between them.